AC to DC power supply having zero frequency harmonic contents in 3-phase power-factor-corrected output ripple

Abstract

An AC-DC power supply circuit utilizing an output stage configuration designed to achieve no output ripple at the power line frequency. To eliminate the ripple formed, each separate processing output stage corresponding to a respective ac voltage source phase which provides a 120 Hz ripple, is stacked, in a series connection, and due to their respective ripple phase shifts of 120° degrees, achieves ripple cancellation at the output.

1. An AC-DC power supply comprising:
 a 3-phase AC voltage source providing balanced 120° phase-shifted input voltage signals at a power line frequency; 
 an active power-factor corrected (PFC) circuit associated with each phase, each PFC circuit receiving a respective AC input voltage signal of a respective phase and providing respective DC signal carrying a ripple voltage of a respective phase; 
 a respective output filter circuit for attenuating said ripple voltage of said respective phase; 
 an isolation circuit coupling said respective DC signal to each respective output filter and ripple voltage of said respective phase to provide a respective isolated DC output voltage; 
 said output filters of each phase forming a stacked series connection, wherein each respective isolated DC output voltage are added together to form an output DC signal and each ripple of each respective phase are added together and cancelled such that said ripple voltage at the power line frequency is eliminated. 
 
     
     
       2. The AC-DC power supply of  claim 1 , wherein each said output filter includes:
 a DC voltage line output line and a reference output line; and 
 a reverse voltage protection circuit connecting said DC output line with said reference line, wherein an output line of a first of said stacked output filters is coupled to a reference line of a next output filter of said stacked series connection. 
 
     
     
       3. The AC-DC power supply of  claim 2 , wherein a reverse voltage protection circuit includes a reverse biased diode device. 
     
     
       4. The AC-DC power supply of  claim 1 , wherein said input voltage ranges between 103 Vac to 132 Vac. 
     
     
       5. The AC-DC power supply of  claim 1 , wherein said input voltage is at 60 Hz+/−5%. 
     
     
       6. The AC-DC power supply of  claim 1 , wherein said input voltage ranges between 198-242 Vac at 50 Hz+/−5%. 
     
     
       7. The AC-DC power supply of  claim 1 , wherein said 3-phase AC voltage source is a Y-configuration. 
     
     
       8. The AC-DC power supply of  claim 1 , wherein said 3-phase AC voltage source is a Δ-configuration. 
     
     
       9. The AC-DC power supply of  claim 1 , wherein said 3-phase AC voltage source is a three phase voltage source having a balanced input and each phase is 120 degrees phase shifted apart. 
     
     
       10. The AC-DC power supply of  claim 1 , wherein said eliminated ripple voltage at the power line frequency obviates requirement for a large LC output filter to reduce power line frequency ripple voltage.